Gearing



H. J. SCHMICK.

GEARING.

APPLICATION FILED APB..1.6, 1920.

1,384,541. 1 Pan1edJu1y12,1921.

V AAToRA/E a .UNITED STATES PATENT OFFICE.

HENRY I. sOHMIcx, OE WILLIAMSPORT,

PENNSYLVANIA, .ASSIGNOR T SCHMICKA scREW AND GEAR COMPANY, OE WILMINGTON, DELAWARE, A CORPORATION OE DELAWARE.

To alwhom it may concern:

Be it known'that I, HENRY J. SOHMIOK, a citizen of the United States, and a resident of Williamsport, in the'cou'ntyof Lycoming l5 andState OtPennsylvania, -have invented an Improvement in Gearing, of which the following. description, in connection with the accompanying drawings, is, a kspeciiicfation, like characters on the drawings repre-` senting'likey parts., v v

`This invention relates to gearing of the type which is commonly termed screw yor worm gearing, and consists' in anew form of tooth, particularly the working facesv of the tooth, whereby certain advantages are secured ascompared with` screw and worm gearing of usual form. y The .objec'ts and advantages of the invenltion may be understood Jfrom the 2vfollowing description of the nature .of the invention and the principles upon which it'operates, and what is claimed'as the invention is set forth inthe appended claims, reference being made to the accompanyingdrawings by wayofillustration of a preferred form of the' invention. In the vdrawings,"Figure 1 is a diagram showing a vpreferred 'method `of generating one form of tooth comprised inthe inventiongv. Fig.' 2 is aside view of a partly finished gear lor @worm embodying the invention, the light lines indicating '(much `elaggerated) the shape and natnreof the workingfaces of the teeth;

form offgear having two'threads ;y'

VFig. 4:A is a diagrammatic .viewv representing a developmentpof a portion of the Asur- Vface of aggear which hasbeen linedoif to indicatejthe relative f peripheral andv axial displacement of successive cuts of the lgenferatingy tool .whereby "diierent pitches may bei'ormed; Y, v a l ,Figsf 5 6; and 7 are diagramsillustrating the overlapping of the successive cuts made in generating a( gear by a square end cutting tool; a' round. point cutting' i001., andasharp pointed vor Vlg-thread v cutting ltool respectively, Athe portionof'the cut which remains inthe nishedgearjgbeing `shown inlheavy Appnclama me@ April 1e,

Y Fig. 3 is a snn'lar viewi of a modified GEARING.

1920. Serial No. 374,468.-

working faces ofthe thread are composed of v lstraight. line elements which may be extended tointercept the axis of the gear at a constantangle. Y In gears embodying my invention,'the Yworking faces of the thread (whether single or multiple),v are composed ofrnarrow strips of surfaces of revolution the centers of curvature .of which lare eccentrically disposed about the axis of the gear,

each center-also being laterally displaced .-in an axial direction with reference to thefcenters of; adjoining strips. V

A suitable method and machine or generating a gear embodyingl the invention is' disclosed in application for. S.

patent led December 111919A(Serial No. 344,265) Y for improvements in method of .and means for generating mechanical elements; but any f suitable methodor machinemay .be used..

f The' particular" form of the invention shown in the drawings has atooth `of approximatelyY truncated VV-sh'ape, and may be produced as follows:

Referring to Fig. 1 thegear blank 11 is iixedfto Ythe faceplate 12`and'arranged to be turned through successive small angles on itsaxis by an index device which may be of 'any suitable kind, such as a pin 13 fitting the series fof'holesflll. The face plate and index mechanism a'rerotatable about the centeraxis Bof the machine to present the outer segment of the blank to the action of the ycutter 15 at each rotation to -cut an arc shaped groove. A seriesof rsuchgrooves 16 are shown in vthefigure.

f. Between successive cuts the index mechanism is operated to cause successive seg- 'ments of the blank to be presentedV to the tool, and the tool is moved laterally (lengththreads.

wise of the main axis of the machine) to cause `the successive cuts to be displaced slightly axially of the blank, thereby generating a stepped `groove on the blank following the general direction of` a helix. If more than one thread isto be cut the axial displacement of the successive cuts must be increased in proportion'to the number of In cutting a plural number of threads, it is desirable to use as many cutters as threads, mounting them side by side, spaced apart a v'distance equal to the pitch. A worm 17 p'rovided'with single thread isshown in ig. 2, and a worm 18 provided with a doublethread is shown in Fig. 3. Fig. 4

'illustrates the effect of doubling the lateral displacement to with respect to the angular displacement y of the successive'cuts 19, as shownvby the dotted outline 19.

" The eccentricity of the axis Aiof the blank with respect to the principal axis B (see `Fig. 1) `may be varied so asrto produce a greater or less degree? of curvature of'` the elements constituting the workingV surfaces of the tooth jas shownat B for example. Also the point of the cutting tool ma be fiat, -rounded or sharp or square resu ting inthe formation of threads as shown in Figs. 4,5, 6 and-7. f 3

In- F ig. 8,4the blank 2O is mounted" on faceplate 21 vbetween the centers 22 of the machine. The blank may be indexed 'around erated be used as a hob to cut a suitable wheel to mesh with it. ,Y j

.From the foregoing description it is evidentthat gears embodying my invention have their vworking faces. composed. of a series of adj oiningl similarly shaped elements of curvilinear form disposed substantially at right angles to the main axis of rotation (see 4ig. 9) and with their respective centers of curvature nonconcentrically disv posedy about and along the main axis of ro-` l tation. If a straight sided cutteriis usedV in generating the gear these elements willl be strips of conical surfaces having their apices arranged in ahelix of the same axial pitch as the lead of the gear;

It is obvious that considerable latitude in the shape of the cutter is permissible, and ythat the depth of cut and lateral displace'- ment ofl the cutter may be adjusted to suit the pitch and lead desired.

The invention is not restricted to the apparatus shown and described, nor to the'particular inodey of operation thereof, nor to the precise forms of gear shown-in the drawing.

I claim the followingasmy invention:

1. A gearV having teeth withtheir working faces composed of a seriesV of adjoining elementary surfaces of curvilinear form each consisting of coaxial arcsdispose'dfin.

parallel planes substantially at right langles tothe axis of rotation of the gear, respective centers of curvature ofsaid elementary surfaces being ,oncmcentricallyl `disposedy about said axis. y j Y C 2. A' gear having teeth with their vworking faces composed of a series of elementary surfacesof curvilinear-form disposed with their axes of curvaturev parallel tothe axisof rotation of said `gear and vwith their respective centers ofl curvature jspirally disposed about said" axis, said 'elem'entary "surfaces conforming to strips of 4conical surfaces hav ing their apicesarranged inafhelixl ofthe same axial pitch 'asthelead of'the'gear. Y

soY

3. vA gear-having teeth extendingaround. j

the axis of rotation, theworking .facesof the teeth being composed of successive Ystrips disposed transversely to saidfax'is and of conical shape of greater radius ofcurvature than theradius of lthe gearyat correspond-` ing points.

Y 4. A gearfhaving teeth extending around' the axis of rotation, the `working facesA of the` teeth being composed of successive strips disposed transversely to said axis and of conicalshape of; greater radius of curvature than the radius of the gear at corresponding points,- the bottom portions of said teeth lbeioe ing composed of overlapping similar porj tions of surfaces of revolution of greaterfradius than the root diameter of the teeth.

5. A gear provided with a thread-`the workingfaces of which are `composed of adjoining narrow 'strips of surfaces lof revolu- .tion having their` respective centers ofV cur.- vature non-concentrically disposed about` the axisof the gear. a

f 6. A rotary member having peripheral.

groove the side wallsoffkwhich comprise a :lio

series of adjoining iaxially'spaced elementary Y surfaceshaving centers of curvature remote y t 7, A Vrotary, member having a series ofV from ther axis of said rotary member.

overlapping cuts inl its-perimetertransverse to the Iaxis of said member, said ,cutsl being .axially spaced l.' whereby theyfmerge into a 'groove making an angle to l"theraxis of said member. j j, Y 8. A rotary. member havlng afseries of overlapping cutsV 1n its perimeterftransverse to the axis'of said member, said cuts having convex side wallsfof greater Vradiusof curva'- ture than theirrespective distances from the axis of said member yand beingV axially groove.

9. An article of the character described having a principal axis of rotation and a Working Jface composed of a series of nonradial linear elements converging in groups at eccentric points spaced lengthwise of said laxis and angularly around said axis, the linear elements of each group of said series 10 conforming substantially to the surface of a cone having its axis parallel to the axis of said article. y

In testimony whereof I have signed my name to this specification.

HENRY J. SCHMICK. 

